1. Field Of The Invention
The invention relates to a method of fabricating a blade for a cutting tool, in particular for a knife, a pair of scissors, a saw, a household appliance (which may optionally be electrical), or indeed an industrial machine, the blade having at least one cutting edge extending over at least a portion of its periphery.
2. Brief Description Of The Related Art
In the meaning of the invention, a cutting tool of a household appliance includes chopper or slicer blades, regardless of whether the cutting tool possesses a blade provided with an edge that is rectilinear or not rectilinear, and regardless of whether it is driven manually or by external motor drive. By way of example, the tool may be an industrial machine having a circular blade, or indeed an annular blade, and suitable for use in the agrifood business, and in particular in slaughter houses.
Such blades are used for slicing or cutting various materials and they are made of metal or metal alloy. In particular, such blades are made of stainless steels of hardnesses that are adapted to the use intended for the tool. In all cases, such steels advantageously comply with the standards and/or regulations in force concerning food-grade materials, i.e. the physical and/or chemical properties of materials that come into contact with food. It is also possible to encounter blades made from one or more ceramics or other materials suitable for cutting or slicing when used under particular conditions.
What these blades have in common is being provided with at least one cutting edge, said edge forming the zone of the blade that comes into contact with the material for cutting, via at least one point. Such blades are liable to present premature wear of the cutting edge, in particular when used repeatedly and/or when used badly. It is then necessary to re-form the cutting edge by sharpening, filing, or grinding. In any event, this operation cannot be repeated indefinitely. It requires the cutting edge to be formed in a zone of the blade, close to the back of the blade and of thickness that increases each time this operation is repeated.
Methods are known in which the cutting edge is of hardness greater than the hardness of the remainder of the blade in order to limit wear thereof. In particular, WO-A-03/000457 describes a method in which, on the blade of a saw, material is deposited in powder form, mixed and solidified with the help of a laser, prior to being shaped to form the cutting edge. The cutting edge is formed between two rollers of the rolling mill type, which serve to form the cutting edge while hot. The laser serves to bring the material up to temperature. Such a device is particularly adapted to blades in strip form, but it is not suitable for use on any type of blade. In addition, the bond between the body of the blade and the shaped material is not as good as it might be.
So-called “facing” methods are also known in which a covering of hard material is deposited on an edge of a cutting blade. Such methods, e.g. making use of microwelding, are described in Patent Abstracts of Japan, Vol. 2000, No. 17, JP-A-01029288.
Patent Abstracts of Japan, Vol. 0120, No. 27, JP-A-62 18 1836 describes using a film for facing the cutting edge of a blade by ion plating. That can also be done by vaporization under the effect of a flame as described in EP-A-0 707 921. It is also possible to envisage depositing make-up material on a blade after heating the material to a temperature below its melting temperature and pressing it against the body of the blade so that it adheres thereto, prior to forming the cutting edge, and this is described in particular in DE-A-3 208 153.
In none of those documents is there described a method enabling a make-up material to be bonded in effective and durable manner with the remainder of the blade so that once the cutting edge has been formed the strength and mechanical properties of the assembly are preserved.
Those are the drawbacks that the present invention seeks more particularly to remedy by proposing a method of fabricating a blade that enables the cutting edge of the blade to be preserved, and thus enables the lifetime thereof to be increased.